2 - Adsorbents

Abstract

An adsorbent material must have a high internal volume that is accessible to the components being removed from the fluid to be technically effective in a commercial separation process, whether this be bulk separation or purification. Such a highly porous solid may be carbonaceous or inorganic in nature, synthetic or naturally occurring. The adsorbent must possess good mechanical properties such as strength and resistance to attrition and good kinetic properties—that is, it must be capable of transferring adsorbing molecules quickly to the adsorption sites. The high internal surface area of an adsorbent creates the high capacity required for a successful separation or purification process. In most applications, the adsorbent must be regenerated after use, and therefore, it is desirable that regeneration be carried out efficaciously and without damage to mechanical and adsorptive properties. The raw materials and methods for producing adsorbents must be not exorbitant for adsorption to compete successfully on economic grounds with alternative separation processes. This chapter discusses adsorbents and their characteristics. It also presents accounts on activated charcoal, carbon molecular sieves, carbonized polymers and resins, silica gel, activated alumina, and zeolites. This chapter closes with a discussion on various applications of adsorbents.